It is known that halogenated benzene compounds may be alkylated by the Friedel-Crafts reaction by acid catalysis (MARCH, Advanced Organic Chemistry, 1977). The known method favors alkylation of the benzene compounds at the para position. For example, alkylation of metadichlorobenzene by the known method produces predominantly 2,4-dichloroalkylbenzene, with a lesser amount of 2,6-dichloroalkylbenzene being produced. In addition, during acid catalysis, the alkyl chain of the alkylating agent tends to be rearranged when the chain is sufficiently long to permit such rearrangement. For example, when n-butyl bromide is used as the alkylating agent, an isobutyl group rather than an n-butyl group is attached to the benzene ring.
One consequence of the limitations of the prior art process discussed above is that it is not possible by that process to produce from a dihalobenzene, which has a hydrogen atom whose two ortho positions are occupied by halogens, major quantities of an alkylated benzene product in which the alkyl group is positioned in the ortho position with respect to the two halogen groups. In addition, it is not possible to produce major quantities of certain alkylated benzene products by that process because of the rearrangement of certain alkyl groups described above.